Cam filter wheel

Abstract

A cam filter wheel apparatus is disclosed for tilting interference filters in order to achieve variation in the light wavelength transmitted by each filter. The wheel apparatus contains a number of filters each mounted so as to pivot and change its inclination with respect to an incident light beam as the filter wheel rotates each filter through the light path. The pivot motion is achieved by a cam follower associated with each filter which rides on a stationary cam track.

I claim: 
     
       1. Optical apparatus for continuously varying the bandwidth of light illuminating an object, comprising a source of wide band light for illuminating an object, a filter wheel assembly having a plurality of narrow bandwidth optical interference filters mounted on said wheel assembly, means to rotate said filter wheel about its axis, said interference filters being pivotally mounted on said wheel and positioned relative to the light path defined between said light source and the object such that said filters are swept through said light path individually during rotation of said wheel, means to cause said filters to pivot with respect to said wheel assembly as they are each swept through said light path so as to change their inclination with respect to said light path, whereby the wavelength of the light passing through each of said pivoting filters is varied in accordance with the variation of said inclination of the pivoting filters, said means to cause said filters to pivot comprising a cam track and a cam follower attached to each filter and riding upon said cam track as said filter wheel assembly sweeps each filter through said light path. 
     
     
       2. The apparatus of claim 1, wherein said cam track is stationary, circular and coaxial with the axis of said filter wheel assembly and each said cam follower rides on said track continuously as said filter wheel assembly rotates. 
     
     
       3. The apparatus of claim 2, wherein said cam track is provided with a rise to be engaged by each cam follower as the corresponding interference filter is swept into said light beam. 
     
     
       4. The apparatus of claim 3, wherein said interference filter pivots through an angle of approximately 45 degrees as the filter is swept through said light path. 
     
     
       5. The apparatus of claim 3, wherein the cam track is shaped so as to compensate for any nonlinearity of the wavelength variation of the light transmitted by said filter versus the interference filter inclination as the latter is pivoted across the light path. 
     
     
       6. Optical apparatus for continuously varying the bandwidth of light illuminating an object, comprising a source of wide band light for illuminating an object, a filter wheel assembly having a plurality of narrow bandwidth optical interference filters mounted on said wheel assembly, means to rotate said filter wheel about its axis, said interference filters being pivotally mounted on said wheel and positioned relative to the light path defined between said light source and the object such that said filters are swept through said light path individually during rotation of said wheel, means to cause said filters to pivot with respect to said wheel assembly as they are each swept through said light path so as to change their inclination with respect to said light path, whereby the wavelength of the light passing through each of said pivoting filters is varied in accordance with the variation of said inclination of the pivoting filters, the initial inclination of said interference filters with respect to said light path being adjustable to any angle.